• The Journal of the Korea Contents Association
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• v.7 no.12
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• pp.303-310
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• 2007

Compressed video bitstreams are intended for real-time transmission over communication networks. Because video compression algorithms eliminate the temporal, spatial, and statistical redundancies, the coded video bitstreams are very sensitive to transmission errors. We propose an error resilient video coding technique to limit the effect of error propagation in low bit-rate video coding. The success of error resilient coding techniques relies on how accurately the transmission errors can be detected. To detect the transmission error, we propose a very simple error detection technique based on data hiding Next, we conceal the corrupted MB data using intra MB refresh and motion compensation with the estimated motion vector and compare the simulation results. This method will be useful in video communication in error Prone environment such as WCDMA networks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.175-181
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• 2010

In this paper, we propose a novel hardware architecture for Rate control module for real time full HD video compression. In the proposed architecture, QP is updated by using the rate control algorithm to every the macroblock line(120MB for Full HD, 20MB for CIF image). Since there are many complex arithmetic and floating point arithmetic in rate control algorithm of JM for H.264, it is impossible to process the rate control algorithm using the integer arithmetic CPU core. So we adopted floating point arithmetic unit in our architecture, and implemented the rate control algorithm using the floating unit. With this implemented hardware, the implemented hardware is verified to be operated in real time.

• Journal of IKEEE
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• v.16 no.4
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• pp.382-388
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• 2012

An H.264/AVC fast motion estimation methodology is presented in this paper. Advanced SIMD based NEON which is one of the parallel processing methods is supported under the ARM Cortex-A9 dual-core platform. NEON is applied to a full search technique with one of the various motion estimation methods and SAD operation count of each macroblock is reduced to 1/4. Pixel values of the corresponding macroblock are assigned to eight 16-bit NEON registers and Intrinsic function in NEON architecture carried out 128 bits arithmetic operations at the same time. In this way, the exact motion vector with the minimum SAD value among the calculated SAD values can be designated. Experimental results show that performance gets improved 30% above average in accordance with the size of image and macroblock.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.556-563
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• 2009

HMIP, an extending version of MIP, makes the signaling traffic low, thereby reducing the packet losses and delay. However, it still has the same problem in MIPv6 in the case of macro mobility, though it can reduce the out-signaling in the case of a micro mobility, a regional mobility with the MAP protocol. To overcome this problem, this paper proposes a handover which exploits an address insurance with selective buffering for the HMIP macro handover. This scheme can decrease the lost packets and the delay time and provide better performance for high QoS traffic and real-time multimedia transmission. The simulation result shows that the proposed scheme makes the transmission delay time and the lost packets smaller than the existing schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1567-1576
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• 1999

In this paper, we propose new methods to detect a scene cut and a dissolve region in compressed MPEG video sequences. The scene cut detection method uses edge images obtained using DCT AC coefficients and the dissolve detection method utilizes the macroblock type information of the MPEG stream. The proposed scene cut detection method is insensitive to brightness and can detect scene changes more precisely than the methods using DC coefficients since AC edge images can express original images more exactly than DC edge images do. The proposed dissolve detection method using the number of intra macroblocks(MBs) computationally efficient since it does not require the decoding process. Experimental results show that the proposed methods perform better in detection scene changes than conventional other methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.339-347
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• 2012

Femtocells as home base station for indoor coverage extension and wideband data service, have been studied with significant interests. When femtocell is deployed, the existing cell structural of changes causes various technical problems. In this paper, we investigate the femto-macro cell interference mitigation in OFDMA system. We propose dynamic downlink resource management scheme which adjust the transmitted power of femtocell according to the strength of received macrocell signal and allocates subcarrier to femtocells in a dynamic manner. In this way, the interference between the macrocell users and femtocells is reduced. The simulation results show that proposed scheme enhances both macrocell and femtocell throughputs.

• Journal of the Korea Institute of Building Construction
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• v.17 no.4
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• pp.321-329
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• 2017

Concrete is a semi-brittle material, so its compressive strength is high but its tensile strength is low. The use of fiber-reinforced concrete to improve the disadvantages of such concrete can be an effective way to toughen effective toughness, and the performance is improved by using steel fiber reinforced concrete for structures that are vulnerable to bending forces. However, alternative materials are required due to corrosion of steel fiber and lowering of workability. The purpose of this study is to evaluate the availability of replacing steel fiber reinforced concrete by evaluating physical properties, mechanical properties and drying shrinkage properties of concrete using macro forta fiber with excellent diffusibility. Experimental results show that the macro forta fiber has better fluidity and mechanical performance than the steel fiber reinforced concrete. It was also confirmed that the crack resistance of concrete using Macro Forta fiber is effective in improving structural cracking and drying shrinkage resistance compared to steel fiber reinforced concrete.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1359-1365
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• 2008

The portion of header in H.264 gets higher than those of previous standards instead of its better compression efficiency. Therefore, this paper proposes a new technique to compress the header of H.264. Unifying a sentence elementary in H.264, H.264 does not consider the distribution of element which be encoded and uses existing Exp-Golomb method, but it is uneffective for variable length coding. Most of the header are block type(s) and motion vector difference(s), and there are redundancies in the header of H.264. The redundancies in the header of H.264 which are analyzed in this paper are three. There are frequently appearing symbols and non-frequently appearing symbols in block types. And when mode 8 is selected in macroblock, all of four sub-macroblock types are transferred. At last, same values come in motion vector difference, especially '0.' This paper proposes the algorithm using type code and quadtree, and with them presents the redundant information of header in H.264. The type code indicates shape of the macroblock and the quadtree does the tree structured motion compensation. Experimental results show that proposed algorithm achieves lower total number of encoded bits over JM12.4 up to 32.51% bit reduction.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.53-59
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• 2005

In this study, the supercritical electroplating was investigated by forming macroemulsion of electroplating solution using surfactant in supercritical $CO_2$. The fluorinated analogous AOT surfactant, sodium salt of bis (2,2,3,3,4,4,5,5-octafluoro-1-pentanol) sulfosuccinate which has both '$CO_2$ philic' chains and 'hydrophilic' head group was used as a surfactant, and Ni plate and Cu plate were used as the anode and the cathode, respectively. Electroplating was carried out in the conventional method and the supercritical macroemulsion and both results were compared. The supercritical electroplating was carried out in various concentration of surfactant such as 2, 4, 7 wt%, the volume ratio of Ni-plating solution to $CO_2$ was varied in the range of 10-70 vol%, and propane was used as a supercritical fluid instead of $CO_2$. According to the experimental results, the plated surface of Ni on Cu plate performed in supercritical macroemulsion was better than that, in conventional state. In the image of Ni surface plated on Cu plate in supercritical state, there were fewer pin-holes and pits comparing with that in the conventional process. The current and conductivity was increased as the volume ratio of Ni-plating solution to $CO_2$ was increased and the current and the amount of Ni plated on Cu plate were decreased as the concentration of surfactant become higher. In addition, in case of the continuous phase, using $CO_2$ was more effective than using $CO_2$.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.263-271
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• 2005

HPFRCC(High Performance Fiber Reinforced Cementitious Composite) is a class of FRCCs(Fiber Reinforced Cementitious Composites) that exhibit multiple cracking. Multiple cracking leads to improvement in properties such as ductility, toughness, fracture energy, strain hardening, strain capacity, and deformation capacity under tension, compression, and bending. These improved properties of HPFRCCs have triggered unique and versatile structural applications, including damage reduction, damage tolerance, energy absorption, crack distribution, deformation compatibility, and delamination resistance. These mechanical properties of HPFRCCs become different from the kinds and shapes of used fiber, and it is known that the effective size of fiber in macro crack is different from that in micro crack. This paper reports an experimental findings on the mechanical properties of HPFRCCs reinforced with the micro fiber(PP50, PVA100 and PVA200) and macro fiber(PVA660, SF500). Uniaxial compressive tests and three point bending tests are carried out in order to compare with the mechanical properties of HPFRCCs reinforced with micro fibers or hybrid fibers such as compressive strength, ultimate bending stress, toughness, deformation capacity and crack pattern under bending, etc.,